1. Field
The present specification generally relates to absorbent structures for capturing carbon dioxide (CO2) from a gas stream and, more specifically, to absorbent structures having designated reaction flow channels with sorbent surfaces and designated heat-exchange channels with water-impermeable barrier layers.
2. Technical Background
Carbon dioxide is a greenhouse gas that has been linked to global warming. It is often a by-product of various consumer and industrial processes such as, for example, combustion of fossil fuels, purification of natural gas, and oil recovery systems. From an economic perspective, carbon trading and future regulations of carbon emissions from flue gases and other CO2 point sources encourage the development of CO2 capture technologies.
Carbon-dioxide capture by solid sorbent can be realized by processes such as thermal swing adsorption, pressure swing adsorption, or vacuum swing adsorption. In thermal-swing adsorption processes, for example, CO2 from a process gas is adsorbed onto a solid sorbent at a low temperature and then is desorbed from the sorbent into an exhaust stream by heating the sorbent to a higher temperature. Once the CO2 is desorbed from the sorbent, the sorbent must be cooled again to begin a new adsorption cycle. In large-scale applications involving thermal-swing processes, the need to cycle temperature quickly and uniformly across a large amount of solid sorbent remains a technical challenge.
Accordingly, ongoing needs exist for alternative methods and apparatuses that may be used in thermal-swing adsorption processes to recover CO2 from process-gas streams.